The invention relates to a hybrid drive train including an internal combustion engine, an electric machine and a transmission provided with at least one torsional vibration damper.
In order to reduce torsional vibrations in the drive train of a hybrid drive, in practice one or more torsional vibration dampers (TVD) are used. A typical arrangement consists of one TVD between the engine rotational mass and the electric machine, and a further TVD between the electric machine and the transmission input shaft. This arrangement forms a three-mass vibration system in which the resonance frequency of the electric machine falls within the frequency range which is excited especially by 4-cylinder engines by the main order (second order). This results in disturbing excessive humming noises particularly in the low-speed driving range.
Furthermore, dual mass flywheels with spring and damping systems are known from DE 35 45 857 C1 and DE 36 09 149 C2, in which in the effective direction a resilient mounting arrangement with one or more dampers in the form of slip clutches are arranged in series for connecting a first flywheel element and a second flywheel element.
It has been found however that the operating behavior of drive trains of hybrid drives provided with known flywheels is unsatisfactory.
It is the principal object of the invention to provide means for reducing humming noises in the low-speed driving range in vehicles with a hybrid drive.